Post on 31-Dec-2015
description
Interfacial Structure of Pickering EmulsionsKjersta Larson-Smith and Prof. Danilo Pozzo
University of Washington Chemical Engineering, Seattle WA
• Particle stabilized emulsions (Pickering) form during the processing of organic fluids in the presence of water and solid micro and/or nanoparticles.
• Particles are enriched at the oil-water interface due to a favorable energy of adsorption.
• Stabilization may be electrostatic or can occur through the creation of an elastic shell that prevent drop coalescence.
• Emulsion stability is controlled primarily by the organization of solid particles at the interface.
• Project goals: – Develop an experimental toolbox to probe the interfacial organization of the particles in the emulsion. – Probe interfacial transitions that occur in Pickering emulsions that are subjected to destabilizing freeze-thaw cycles.
Oil
Model Emulsions: Hexadecane stabilized by functionalized gold and silica nanoparticles (4-100 nm)
Small Angle Neutron and X-ray Scattering Electrostatic Stabilization
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+ ++
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+ ++
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Electrostatic Stabilization
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+ ++
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+ ++
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Electrostatic Stabilization
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+ ++
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+ ++
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Steric StabilizationSteric Stabilization
10-2
10-1
100
101
102
103
104
105
106
I(q)
(cm
-1)
10-5
10-4
10-3
10-2
10-1
100
q (Å-1
)
SANS/USANS 16nm SiO2 Pickering Emulsion Model Fit
Water
50 m
Electrostatics dominate nanoparticle stabilized emulsions